Jessour is a water harvesting method within the category of macro‐catchment and floodwater methods (Wadi‐bed systems). The wall/dyke structures are built across relatively steep wadis in southern Tunisia and function as barriers that hold back sediment and runoff water.

The walls are usually high to account for the steep slopes. They are made of earth, stones or both; but always have a spillway, usually made of stone. Over several years, as water is stopped behind these walls and sediments settle and accumulate, new land for planting is created which is mainly used to cultivate figs and olives but also other crops. In the cropping area water is collected from the catchment through the wall structure and therefore trees can be grown.

Jessours are mostly in use in semi‐arid to arid areas with average rainfall of around 100 mm peryear, by means of jessours it is possible to reach 400‐500mm of rainfall per year.